header {
  background-color: #435a5b;
  height: 50px;
  font-style: 微软雅黑;
  position: fixed;
  width: 100%;
  z-index: 11;
  img{
    margin-left: 50px;
  }
}
.sidebar{
  background-color: #435a5b;
  width: 17%;
  min-height: 1000px;
  float: left;
  position: fixed;
  border-top:2px solid black;
  margin-top:50px;   
  ul{
    margin-top: 50px;
    li{
      font-size: 18px;
      color: white;
      cursor: pointer;
      text-align: center;
      height: 40px;
      line-height: 2.5;
      &:hover{
        background-color: #435a5b/1.5;
        border-bottom: 2px solid #435a5b/4
      }
    }
  }
}
.view_window{
  float: right;
  width: 79%;
  margin-right: 20px;
  margin-top: 70px;
  border-top:2px solid #435a5b;
  pre{
    text-indent: 20px;
  }
}
@media only screen and (max-width: 500px) {
  .sidebar{
    width: 100%;
    position: static;
    min-height: inherit;
    padding-bottom: 50px;
  }
  .view_window{
    margin-right: 40px;
    margin-top: 50px;
    text-align: center;
  }
}
.group_name{
  height: 30px;
  line-height: 1.4;
  margin-left: 20px
}
.how_use,.demo{
  color: white;
  height: 30px;
  border-radius: 20px;
  background-color: #435a5b;
  font-size: 20px;
  line-height: 1.5;
  word-spacing: 20px;
  text-indent: 20px;
  margin-bottom: 20px
}
.use_content p{
  text-indent: 20px;
}
/*tabs*/
.tab_class{
  color: red;
}
.tabs li {
  float: left; 
  cursor: pointer;
  width: 100px;
  height: 30px;
  line-height: 2;
  background-color: grey
}
/*alert*/
.alert_demo p{
  display: inline-block;
  margin-right: 135px;
  margin-left: 20px;
}
.alert_demo div{
  border-radius: 5px;
  border: 1px solid red;
  width: 300px;
  margin-top: 10px
}
/*modal*/
.modal_demo{
  .modal_opacity{
  display: none;
  width: 100%;
  min-height: 670px;
  background-color: gray;
  opacity: 0.6;
  position: absolute;
  left: 0;
  top: 0;
  }
  .modal_box{
  position: absolute;
  width: 50%;
  height: 35%;
  background-color: white;
  text-align: center;
  font-size: 30px;
  line-height: 5;
  border-radius: 10px;
  color: red;
  display: none;
  .close{
    content: "\e69a";
    font-size: 31px;
    position: absolute;
    right: 7px;
    top: -54px;
  }
  }
} 
